Many observers feared Khan had bitten off more than he could chew by agreeing to face former world champion and veteran welterweight campaigner Collazo on his bow in the 147lb division.

Yet the Bolton fighter - whose last bout was in April 2013, when he struggled badly against the lightly regarded Julio Diaz - showed his class in Las Vegas by knocking down the rugged southpaw three times en route to a unanimous decision victory.

Khan was in no way flattered by two judges scoring the bout 119-104, with the third having it 117-106, as his superior hand speed and much-improved defence frustrated Collazo, who had won his last four fights, including a shock second-round knockout win over highly-rated Victor Ortiz last time out.

"It was tough because Collazo was very awkward, but we pulled it together and came out with the win," Khan said.

"It was a tough fight to debut at 147 pounds after a 13-month lay-off. Not many fighters would take a fight like this.

"I've got a lot of respect for him, he's one of those guys who makes everyone look bad but I'm lucky to have had a great performance against him.

"I knew it was going to be a war, it was going to be a hard, tough fight. I'm glad it's over and now we're going to move onto bigger and better things."

After improving his record to 29 wins from 32 bouts, Khan is now keen to lure Mayweather into what would surely be a lucrative showdown.

The pound-for-pound king extended his remarkable record to 46-0 after grinding out a majority decision victory over Marcos Maidana in the main event at the MGM Grand, and Khan, who has been linked as a potential opponent for Mayweather for some time, is keen to seize his chance now.

"People want to see a fight between me and Floyd," Khan said.

"Floyd hasn't seen speed. He's fighting people with explosive power. But styles make fights and I think my style will give him a lot of trouble.

"Floyd looks beatable. He's getting a little older now and that's why a lot of people want the fight now because they want a young lion to come up and they want to see him get beat. I think the only person who has the chance to do that is me."

However, the bout will definitely not happen in 2014 as Mayweather's next intended fight date in September is too close to the Muslim fasting period of Ramadan for Khan.

That is perhaps just as well for the 27-year-old Khan, as no sooner had Mayweather's win over Maidana been announced than the two combatants began talking about an immediate re-match.

Mayweather was the overwhelming favourite to extend his unbeaten record but he came under some fierce pressure in the opening rounds from Maidana.

The Argentinian underdog came out swinging and caught Mayweather on a number of occasions although the pound-for-pound king gained the upper hand as the fight went on and finished strongly.

While one judge had the fight level at 114-114, the other two scores were 117-111 and 116-112 for Mayweather, whose unerring accuracy eventually saw him chalk up yet another win.

"It was a tough, competitive fight," Mayweather said. "I gave the fans what the fans wanted to see.

"Normally, I box and move. Finally, I was in a tough, competitive fight. Tonight, I wanted to stand there and fight and give the fans their money's worth.

"If the fans want to see it again, we'll do it again."

Maidana, who suffered the fourth defeat of his 39-fight career, clearly felt he had done enough to have been given the nod.

"I definitely think I won this fight," Maidana said. "Floyd did not fight like the man I expected him to.

"He did win some rounds, but the majority of them I dominated. I did go after him, but he's a difficult fighter.

"I have to give him a rematch because I won the fight. I'm not scared of him. Why not give him the rematch?"